Galvanometer.



No. 866,387. PATENTED SEPT'.17, 1907.

J. RICHARD.

GALVANOMETER.

APPLICATION IILBD JAN.27,1905.

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No. 866,387 I PATENTED SEPT. 17, 1907.

J. RICHARD.

GALVANOMETBR.

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No. 866,387. PATENTED SEPT. 17, 1907.

J. 310mm); GALVANOMETER.

APPLICATION FILED JAN.27.1905.'

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No. 866,387. PATENTED SEPT. 17, 1907.

J. RICHARD.

GALVANOMETER.

APPLIOAIION FILED JAR. 27,1906.

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UNITED STATES JULES RICHARD, OF PARIS, FRANCE.

GALVANOMETER.

Specification of Letters Patent.

Patented Sept. 17, 1907.

Application filed January 27, 1905. Serial No. 242,895.

To all whom 'it may concern:

Be it known that I, J ULES RICHARD, of 25 Rue M- lingue, in the city of Paris, Republic of France, optician and instrument maker, have invented Improvements in Galvanometers, of which the following is a full,

clear, and exact description.

This invention has for its object improvements in galvanometers of the kind of which the value of a current is obtained by the observation or registration of the angular deflection, produced by the action of this current, of a movable system formed syn frame of metal wires connected to the poles of the source of electricity and moving in the magnetic field of one or more permanent magnets.

These improvements have for their object to increase the sensitiveness of the apparatus by increasing the value of the couple producing rotation, that is to say, by enabling the electromagnetic field produced by the current to act with a constant and maximum intensity on the stationary magnetic field, and they also permit the use of a lever-arm which is considerably longer than those in the forms of galvanometers heretofore known. This result is obtained by moving, in an uniform magnetic field, two of the sides of a galvanometer coil, of which all the parts are eccentric to the axis of rotation, in such a manner as to increase the stability of the moving system.

The object of the invention will be hereinafter described with reference to the annexed specimen drawing, in which:-

Figure 1 represents a preferred form of the apparatus in front elevation. Fig. 2 shows it in side elevation. Fig. 3 is a detail sectional view of one of the supports of the axis of rotation on an enlarged scale. Figs. 4, 5 and 6 show respectively in front, side and plan View, the galvanometric frame; and Fig. 7 is a horizontal section of the improvement on an enlarged scale.

In these figures, the sameletters of reference indicate the same parts.

. The galvanometer represented in the drawing comprises, as its fixed magnetic system, two magnets a and b having the same section and the same development (71. e. length when straightened out), and consequently the same weight, and the same magnetic constants. These magnets have their pole-pieces a and b cylindrical and concentric, the former concave and the latter convex. In the spaces included between their opposite surfaces, there are two very intense uniform magnetic fields, in which move the two active sides of the galvanometer-coil c which is carried by a damping frame made of a metal of very high conductivity, for example, electrolytic copper, silver, etc. This movable system, shown in Figs. 4, 5 and 6, is formed of two pieces (I d each made of a single strip of metal, which are secured together at a definitive angle. In the middle part of each strip, which is stamped or otherwise formed into a portion of a cylindrical surface, is wound the galvanometer-coil c, the two other parts or sides of which coil extend along chords of the basal circles of the said cylindrical surfaces. The whole of this system is, as will be seen, eccentric relatively to the axis of rotation, which coincides with the axis of the cylinder, that is to say, the plane of the winding does not pass through the axis of rotation.

By reason of the arrangement of the magnetic field and of the coil which moves in this field, the electromagnetic forces, which move the movable system, act with a constant intensity simultaneously on the two active parts of the frame, of which the eccentric mass, balancing the system, contributes to its stability.

The axis of rotation e, of large cross-section, simultaneously serves to stay the sides of the frame and to diminish its electric resistance in such a manner as to increase its damping action. The axis or arbor c (Fig. 3) is terminated by two pivots f turning in holes having end-stones or plates 9 held by springs h on a guide 71/ in a casing k for the purpose of preventing breakage of the pivots during transport and mounting. The spring may be adjusted by a hollow screw h through which the guide h passes.

The two ends of the galvanometer coil are respectively connected to two spiral springs i which serve to introduce the current and to balance the electromagnetic action thereof.

The axis of the movable system bears either a pointer moving in front of a graduated scale, in the case of an indicating apparatus, or a stylus terminated by a pen if it is registering galvanometer. In the accompanying drawing, the needle or pointer ,7 is mounted on pivots on a piece k which turns with the axis of rotation. This needle bears a pen Z, a pressure of which on the drum m can be regulated according to the vertical, horizontal or inclined position given to the apparatus. This regulation is effected by manipulating a screw n acting on the end of the needle. The whole device may be mounted on a frame 0 by means of fastening devices 10. Terminals q are also provided.

The wire, which forms the galvanometric frame 0, possesses different constants according to whether it is desired to use the apparatus as a voltmeter or as an ammeter. In the first case, there is added to the circuit a suitable resistance depending on the maximum voltage which it is desired to measure; in the second case, it is combined with shunts, the dimensions of which vary with the maximum current to be measured.

The magnetic field, which has been described and formed by the combination of two magnets with concentric pole-pieces, may be employed in other apparatus than measuring instruments, such for example, as relays, etc.

The movable system being perfectly balanced, it'is clear that the apparatus can be made to work as Well horizontally as vertically.

Claims.

1. A galvanometer comprising two magnets having polepieces curved on concentric lines, the pole-pieces ofeone being located within those of the other, and a galvanometric coil mounted to turn around the center of the pole-pieces.

2. A galvanometer comprising two magnets having pole; pieces curved on concentric lines, the'pole-pieces of one being located within those of the other, and a galvanometric coil mounted to turn around the center of the pole-pieces; this coil having a curved cross-section and being located between the respective pole-pieces.

' 3. A galvanometer comprising two magnets having polepieces curved on concentric lines, the pole-pieces of one being located within those of the other, and a galvanometric coil mounted to turn around the center of the pole-pieces and having two sides moving in the two magnetic iields, this coil being eccentrically located relatively to the axis of rotation 4. A galvanometer comprising two magnets having polepieces curved on concentric lines, the pole-pieces of one being located within those of the other, and a galvanometric coil mounted on a V-shaped frame having one of its sides moving in each of the magnetic fields.

5. A galvanometer comprising two magnets located opposite each other and each having pole-pieces curved on the arcs of a circle, the pole-pieces of these two magnets registering element, and a galvanometric coil mounted upon this frame and having two sides moving in the two magnetic fields constituted by the concentric polepieces of the two magnets.

6. A galvanometer, comprising a pair of magnets located opposite each other and each having pole pieces curved on the arc of a circle, the circles on which the pole pieces of the two magnets'are curved being concentric with each other, and the pole pieces of one magnet being located within those of the other, and a V-shaped frame pivoted at the center of said curves; said frame being provided with a pointed rigidly attached thereto, and with projections having a coil of wire thereon, said coil being located between the curved ends of said pole pieces.

7. A galvanometer, comprising a pair of magnets having concentrically curved pole-pieces, and a V-shaped frame pivoted at the center of said pole-pieces, said frame being provided with a pointer rigidly attached thereto, and with projections having a conductingcoil thereon, said coil being located between the curved ends of the pole-pieces. V

The foregoing specification of my improvements in galvanometers signed by me this 7th day of January 1905.

JULES RICHARD. 

